todos ese dithering que usaste entre colores muy similares no funciona realmente. ademas, hay algunos pixeles blancos entre los pelos de la cabeza que se te olvdidaron borrar ]:

There are a few pixels between the hairs and inside the question mark, where you forgot to set the transparency.
Something about the mouth makes me read it as a bump, not as a hole as it should, which I think is because of the lighting.

yep
xD
                        

thats a whole lot of colors for such a small piece